As2066 pallet fork adjustment advise needed

[Dmitry]

Hello,

Working on an as2066, needed a new balance wheel and cock, got the whole assembly from a donor but when I put it in, the new balance assembly clearly gets stuck on the pallet fork.

Removed the pallet fork, the balance wheel goes great with healthy amplitude, breaks as soon as I put the pallet fork in.

It does not get stuck like in an overbaking case, the cock on this caliber allows for adjustment of banking, I highly suspect the mismatch between the balance wheel and the original fork.

Any recommendations?

[JohnR725]

for troubleshooting it's always best if you give us pictures

[Nucejoe]

Does the fork snap side to side? does it hit the banking pins? 

Did it work in donor movement.

 Misaligned pallets can lock the escapement.

This subject  has previously  been discussed  many times on the forum, 

On 9/16/2020 at 9:26 PM, HSL said:

Just looking at the pictures your analyses are spot on, at a closer look the entry and exit seems to also differ in depth these should also be equal in depth.
If their not you get exactly as you say loss in amplitude.

 

 

[Jon]

If you have a donor, have you tried the other pallet fork?

The escapement might be out somewhere. Try checking what @Nucejoehas suggested with a too deep a lock.

Here's a previous thread with slides to explain about checks to do to ensure everything interacts between the escape wheel, pallet and impulse jewel of the balance properly. I would be surprised after performing these checks you don't find the problem fairly quickly. It might be something as simple as a loose impulse jewel or one that is too deep in the notch and hits the guard pin.

 

 

[Dmitry]

Nearly impossible to see anything there when the balance is in, here are a few pics, everything looks in order though.

[nevenbekriev]

Dima, this is actually possible to see. You have to look thru the opening, under the balance, in the direction shown with green arrow. You need to check where the problem is. Actually, when speaking for pallet fork adjustment, one will normally understand the pallets position adjustment in the slots of the pallet fork, and I am not sure if this is the problem. If the pallet fork is original to the movement and 'snaps' as it should and the escape wheel advances when this happens, then this is not the case. You must check how the balance oscillates free without the lever but with the lever bridge in place. Then, with the lever in place but without the escapwe wheel and the other train parts. Removing all from the plate and leaving only the balance and the lever with their bridges gives good possibility to see all from many points of wiew.

I can not be sure, but on the picture there is something marked with red arrow, like result of a hit, and it may limit the movement of the lever to the right and thus make the guard pin rubb in the roller or prevent the pallet to let the wheel tooth pass.